Lubricant for rolling metals



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. 3,041,281 LUBRICANT FOR ROLLING METALS Philip A. Winsor, Willington, and Kenneth A. Lloyd, Barrow, near Chester, England, assignors to Shell Oil Company, a corporation of Delaware No Drawing. Filed Dec. 29, 1959, Ser. No. 862,478 Claims priority, application Great firitain Jan. 30, 1959 7 Claims. (Cl. 25242) This invention relates to improved lubricants, more particularly, it relates to aqueous base lubricants designed especially for use in hot rolling non-ferrous metals, such as aluminum, and for the metal working of ferrous m tals as Well.

It is well known from the prior art that non-soluble oils such as straight mineral oils or their emulsions are unsatisfactory as lubricants for the hot rolling of nonferrous metals such as aluminum. Straight mineral oils or composite mineral oils lack the required cooling properties since the temperature encountered during the hot rolling of aluminum is in the range of from about 300 F. to about 900 F. To take advantage of the lubricating qualities of oils, emulsions have been tried for this purpose, but although they are good coolants they cause staining of the worked surfaces and also cause so-called metal pick-up. This phenomenon is the appearance of nodules or aecretions of metal on the surfaces of the rolls. The accretions build up, causing sticking and de formation, which at times become serious enough to cause shut-down and require regrinding of the rolls. In addition to the loss of time and money, spoilage and waste of metal are the results of improper lubrication.

Other allied problems occur in the cold working of ferrous metals such as steel and the like. When using ordinary prior art metal-working lubricants, drills rapidly become worn and require replacement or regrinding. In the cold rolling of steel it was found that prior art compositions limited the rate at which cold rolling could be conducted.

Compositions comprising aqueous solutions or suspensions of certain polyalkylene glycols showed improvements in certain aspects, particularly in the hot working of non-ferrous metals. However, these compositions eX- hi'bited borderline corrosion characteristics and, more over, resulted in a rolled sheet having a relatively dull appearance, although somewhat improved from the appearance of sheets rolled by the use of still earlier lubricating compositions.

It is an object of the present invention to provide an improved lubricant for metal working. More particularly, it is an object of the present invention to provide an improved lubricating composit on for the hot rolling of non-ferrous metals. It is also an object of the present invention to improve lubricating compositions found to be useful for the cold working of metals including forrous metals such as steel. More particularly, it is an object of the present invention to provide improved aluminum hot-rolling lubricants having good cooling and lubricating properties and providing a bright surface finishing coupled with lack of corrosion characteristics and which is resistant to staining and metal pickup.

Now, in accordance with this invention, a lubricating composition is provided comprising a major proportion of water together with three essential additives: The first additive is present in an amount between about 0.05 and 10% by Weight of the composition and is a water-soluble (hydrophilic) monoether of a polyoxyalkylene liquid compound having an inverse separation temperature relationship, a viscosity at 100 F. SUS of about 500-1500, and an average molecular weight between about 1000 and 10,000. The second essential additive is a hydrophobic monoalkyl ether block polymer of polyoxypropylene and polyoxyethylene compounds utilized in an amount of ODS-10% by weight of the composition. This I Patented June 26, 1962 block polymer contains in its structure hydrophobic polyoxypropylene groups and hydrophilic polyoxyethylene groups, the hydrophobic groups constituting at least about 20% by weight of the copolymer, which has an average molecular weight in the range from about 1000 to about 10,000. The third essential component of this composition comprises 0.01-5 by weight thereof of a hydrophilie polyoxyalkylene compound having an average molecular weight less than about 500, exclusive of terminal radieals.

The combination of the first of these additives with Water results in a composition which has limited use as a hot-rolling lubricant for non-ferrous metals; while it allows for satisfactory hot rolling, it results in a certain amount of corrosion of the rolls and the metal surface is relatively dull, or at least is not as bright in finish as is now desired. The substitution of the second component for the first in an aqueous system results in a twophase composition which exhibits separation unless this is corrected by the presence of emulsifying agents. Moreover, the incompatibilityv of the two constituents, namely, the hydrophobic block polymer and water, sometimes causes gelling of the composition, with attendant difiiculties in its handling and use. The composition which results is so high in lubricity that the roll will not bite into the ingot and, therefore, the latter must be forced between the rolls in order to effect a passage therethrough.

It has now been found that the combination of the water-soluble oopolymer referred to above, together with the hydrophobic block polymer, also referred to, taken together with the relatively low molecular weight polyethylene glycol compound results in an improved composition, the major aspects of which are the reduction in pick up on the rolls and the production of a finished product having a bright surface. In addition, the compostion exhibits the correct degree of lubricity, permitting ready feeding of the ingots between the rolls. Still further improvements are obtained by the addition of minor amounts of corrosion inhibitors, of which the most favored is an alkali metal salt of a fatty acid having from 16 to 30 carbon atoms per molecule.

The hydrophilic monoether of the polyoxyalkylene liquid compound is one having a negative eoefiicient O-f solubility. By this is meant a hydrophilic mon'oalkyl ether of a hetero polyoxyalkylene liquid compound which is completely (3-10%) soluble in water at temperatures up to about 40 C. and'which separates out of water,

thereby forming two liquid phases, at a temperature between about 40 C. and about (3., preferably between 50 and 70 C. Polyoxyalkylene liquids having separation temperatures above' C. and a viscosity (SUS at 100 F.) above 1,000 are unsatisfactory for the purpose of this invention, since they permit metal pick-up.

The polyoxyalkylene liquids having a negative coefficient of solubility which are used in the composition of the present invention are the polyoxyalkylene glycol monoethers having the general formula R -O(R O) H, wherein R represents a hydrocarbon radical, R represents an alkylene radical, and n represents an integer. In the polyoxyalkylene chain (R O) the radical R may be any alkylene radical, preferably an alkylene radical with 2 to 8 carbon atoms. Still more preferred in the compositions of the invention are the polyoxyalkylene liquids in which the alkylene radical is an ethylene or propylene radical.

In the polyoxyalkylene chain (R O) there may be present alkylene radicals with different numbers of carbon atoms. The chain may, for instance, consist of both oxyethylene and oxypropylene radicals. Where the polyoxyalkylene chain contains different alkylene radicals, these may be randomly distributed throughout the molecule or may be arranged in regularly recurring units lar oxyalkylene radicals. Where the polyoxyalkylene chain contains different alkylene radicals, these may be randomly distributed throughout the molecule or may be arranged in r'egularly recurring units or blocks, each consisting of one or a plurality of similar oxyalkylene radicals. When the polyoxyalkylene compound contains both ethylene and propylene radicals, preferably at least 30% of the alkylene radicals are propylene radicals. For

the compositions of the invention preference is given t 'the polyoxyalkylene liquids, in which the radical R is preferred. The higher the molecular weight of the alkylene units in the polyoxyalkylene chain, the lower will be the solubility of the polyoxyalkylene compound, in

water.

Representative of the polyoxyalkylene liquids having a negative coefficient of solubility in water which can be used in the process of the invention are the heteric polyoxyalkylene glycol monoalkyl ethers containing both oxyethylene and oxypropylene units in the chain such as the products commercially available under the trade name Uconf and the polyoxyethylene glycol mono-alkylphenyl ethers such as the products commercially available under the trade name Igepal. Especially suitable compounds are the butyl monoether of a block copolymer containing equal weights of ethylene oxide and propylene oxide, the

butyl monoether of a copolymer containing 60% by weight of ethylene oxide and 40% by Weight of propylene oxide and the octyl phenyl ether of polyoxyethylene glycol containing an average of 9 ethylene oxide radicals per molecule.

The second essential polymer to be used in these compositions is a hydrophobic monoalkyl ether block polytrier of polyoxypropylene and polyoxyethylene compounds containing in its structure hydrophobic polyoxypropylene groups and hydrophilic polyoxyethylene groups,

the hydrophobic groups constituting at least 70% by weight of the copolymer, which has an average molecular Weight of about 1,000 to 10,000, preferably between 1,500 and 5,000. The ether radical at one end of the block polymer chain is preferably an alkyloxy group wherein the alkyl radical has from 2 to carbon atoms, preferably 3-5 carbon atoms, the most preferred species being a butyl ether radical. Other. suitable groups include ethyl, propyl, pentyl, hexyl, octyl, and decyl groups, which may be either straight-chain or branched-chain radicals. The individual blocks of oxypropylene and oxyethylene groups are those having between about 200 and 500 average molecular weight, preferably 250 and 350 average molecular weight each. Methods for the preparation of such block polymers are known in the art.

7 above.

These polymers exhibit substantial water insolubility, since this has been found to be an essential requirement in order to obtain the benefits of the invention referred to This is contrasted to.the water solubility of the previously described polyoxyalkylene compounds which are preferably the heteric copolymers fully soluble in the aqueous component of these compositions. The two types of polymers coact with each other, the watersoluble polymer not only providing its'portion of the 10 metal working lubricating functions but also acting to prevent gelation of the composition due to the presence of the hydrophobic block'polymer. Each of the abovenamed types of polymers is preferably present in an amount between 0.05 and 10% by weight each, but opti- 5- mum results are obtained when 0.15% by weight of each of the polymers is utilized.

. In the absence of an emulsifying agent, this composition would tend to separate into several phases. Many emulsifying agents are not found to be suitable; hence it becomes a problem to select an emulsifying agent which will maintain a stably dispersed system without damage to the properties of the composition. Such an emulsifying agent comprises 0.01-5% by weight of the composition of a hydrophilic polyoxyalkylene compound having 5 an average molecular weight less than about 500- exclusive of terminal radicals. The most suitable type of compound meeting these requirements is a ,polyoxyethylene compound or a polyoxyethylene-polyoxypropylene co polymer, the terminal radicals being hydroxyls, ethers or esters. Most suitably, it has been found that optimum results are obtained when each of the terminal radicals is an ester of a higher fatty acid, preferably one having from 12 to 20 carbon atoms per molecule. Suitable species of such emulsifying agents include the preferred species, namely, polyethylene glycol dioleate, wherein the polyethylene glycol has an average molecular weight of about 250-350. Otherspecies include polyethylene glycol stearate, polyethylene glycol stearate oleate, polyethylene glycol monobutyrate, polyethylene glycol monobutyl ether, and polyethylene glycol-polypropylene glycol dioleate, in all of which cases the glycol has an average molecular weight less than about 500 and preferably between about 250 and 350. While the emulsifying agent may be. present in an amount from 0.01 to 5%, it is preferred to employ 0.05 to 1% by weight of the total composition. 7

Additional components which may be utilized in these compositions include especially the alkali metal salts of higherfatty acids, especially those having from 16 to 30 carbon atoms each, and preferably from 16 to 18 carbon atoms each. Suitable species include sodium oleate, sodium stear'ate, potassium oleate, potassium stearate, lithium oleate, and the like. These alkali metal salts have been found to be especially elfective corrosion inhibitors when utilized in the compositions of this invention. Other sodium salts may be employed, such as those of like myristic or palmitic acids.

Thefollowing table in'which parts are parts by weight gives examples of compositions of the invention: TABLE I Compositions of Blends Blend N 1 2 3 4 5 6 V 7 8 9 10 11 Component 0 V wt. percent propylene oxide, 15 wt. percent ethylene oxide block copolymer sybstantially insoluble in water- 1 1 l l 1 0. 5 l. 5 0. 5 1 1 0. 5

50 wt. percent propylene oxide, 50 Wt. percent ethylene oxide, random copolymer with negative coetfieient of solubilityin water 1 l l 1 1 l. 5 0. 5 0.5 1 1 1. 5 PEG 300 dioleate 0. 1 0.1 0. 1 0. 1 0. 2 0. 1 0. 1 0. l 0. 1 Ethylene oxideloetyl phenol condensation product 0. 05 0. 25 Sodiumoleate; 0. 1 0.1 0. l 0. l '0. 1 0. 1 0. 1 0 1 Triptbannlamino 0. 5 O. 5 0. 5 O. 5 O. 5 0. 5 Diethenolamine. 0. 5 Water 97. 8 97. 9 97. 3 97. 3 97. 3 97. 3 97.8 98. 4 98. 35 97. 15 97. 8

a The dioleate of a polyethylene glycol having a molecular weight of 300.

The following examples illustrate the hot-rolling of aluminum, the cold rolling of steel, and the drilling of steel plates.

EXAMPLE I Ingots 6 inches by 6 inches by 2.75 inches of commercially pure aluminum meeting the 2S specification were heated to 550 C. and rolled in a two-high, singlestand, non-reversing type mill. A peripheral speed of 200 feet per minute was used. The lubricating composition used was blend 1, and the storage tank was kept at approximately 40 C. The sheets produced were shiny and free of tail marks, and of good anodizing quality. There was very little roll coat.

7 EXAMPLE II A 3.5% magnesium-aluminum (54S) alloy was rolled using the same mill as that described in Example I, the lubricating composition being blend 1. The sheets produced were shiny and there was very little roll coating since subsequent rolling of 28 produced sheets which still had good anodizing quality.

EXAMPLE III Using blend 1 as the lubricating composition in the cold-rolling of steel, it was found possible in 5 passes at a roll speed of 100 ft./min. to reduce the thickness of the sheet from 0.050 inch to 0.012 inch.

EXAMPLE V Hot rolling of aluminum alloy 28 Was carried out as described in Example I only using blend 8. The sheets obtained were shiny and free of tail marks, and of good anodizing quality. There was very little roll coat.

The following example illustrates drilling of steel using blend No. l.

EXAMPLE V In this test a /s inch drill, turning at 2900 r.p.m. was fed through a 0.42 inch thick plate at 5.8 thousandths of an inch per revolution. The drill was used until, under these conditions, no more holes could be drilled. In the mean of eight experiments 52 holes Were drilled using blend 1, whereas by comparison using a aqueous dispersion of a conventional E.P. soluble oil only 22 holes were drilled.

In order to preserve the bright finish found to be most desirable in metal working, it is preferred that the composition of the invention have a pH between about 6.5 and about 8.5.

We claim as our invention:

1. An aluminum hot rolling lubricant composition comprising (1) a major amount of water, (2) 0.l5% by weight of a hydrophilic mono-C -C alkyl ether of a heteric oxyethylene-oxypropylene copolymer, the weight ratio of oxyethylene to oxypropylene groups being between lsl and 3:1, having a separation temperature between 50 and 70 C. and a viscosity at 100 F. SUS between about 500 and about 750, (3) 0.l5% by weight of a hydrophobic mono-C alkyl ether block polymer of polyoxypropylene and polyoxyethylene compounds, the hydrophobic polyoxypropylene blocks constituting at least by weight of the polymer which has an average molecular weight of 1,500-5,000 and (4) 0.05l% by weight of a hydrophilic polyethylene glycol diester of a C1240 fatty acid, the glycol having a molecular weight less than about 500.

2. An aluminum hot rolling lubricant composition comprising (1) a major amount of water, (2) 0.l5% by weight of a hydrophilic monobutyl ether of a heteric copolymer of approximately equal weights of ethylene oxide and propylene oxide and having a viscosity of 600-750 SUS at F., (3) 0.l5% by weight of a hydrophobic monobutyl ether of a block polymer of ethylene oxide and propylene oxide, each block having a unit molecular weight between about 200 and 500, the average molecular weight of the block polymer being between about 200 and 3,500 and containing approximately 15% by weight of polyoxyethylene blocks, and (4) 0.054% by weight of the dioleate of a polyethylene glycol having an average molecular weight of 250-350.

3. A composition according to claim 1 containing in addition 0.05 %-2% by weight of an alkali metal salt of a fatty acid having 16-30 carbon atoms per molecule.

4. A composition according to claim 2 containing 0.052% by weight of sodium oleate.

5. An aluminum hot rolling lubricant comprising (1) about 1% by weight of a hydrophilic monobutyl ether of a heteric copolymer of approximately equal weights of ethylene oxide and propylene oxide and having a viscosity of 600750 SUS at 100 F., (2) about 1% by weight of a hydrophobic monobutyl ether of a block polymer of ethylene oxide and propylene oxide, each block having a unitmolecular weight between about 200 and 500, the average molecular weight of the block polymer being between about 200 and 3,500 and containing approximately 15% by weight of polyoxyethylene blocks, (3) a mixture of about 0.1% by weight each of the dioleate of a polyethylene glycol having an average molecular weight of 250-350 and sodium oleate and the balance being water.

6. The composition of claim 5 containing about 0.5% by weight of diethanolamine.

7. The composition of claim 5 containing about 0.5 by weight of triethanolamine.

References Cited in the file of this patent UNITED STATES PATENTS Edmiston June 16, "1931 Beaubien et al. Mar. 4, 1958 OTHER REFERENCES 

1. AN ALUMINUM HOT ROLLING LUBRICANT COMPOSITION COMPRISING (1) A MAJOR AMOUNT OF WATER, (2) 0.1-5% BY WEIGHT OF A HYDROPHILIC MONO-C2-C10 ALKYL ETHER OF A HETERIC OXYETHYLENE-OXYPROPYLENE COPOLYMER, THE WEIGHT RATIO OF OXYETHYLENE TO OXYPROPYLENE GROUPS BEING BETWEEN 1:1 AND 3:1, HAVING A SEPARATION TEMPERATURE BETWEEN 50 AND 70*C. AND A VISCOSITY AT 100*F. SUS BETWEEN ABOUT 500 AND ABOUT 750, (3) 0.1-5% BY WEIGHT OF A HYDROPHOBIC MONO-C2-10 ALKYL ETHER BLOCK POLYMER OF POLYOXYPROPYLENE AND POLYOXYETHYLENE COMPOUNDS, THE HYDROPHOBIC POLYOXYPROPYLENE BLOCKS CONSTITUTING AT LEAST 80% BY WEIGHT OF THE POLYMER WHICH HAS AN AVERAGE MOLECULAR WEIGHT OF 1,500-5,000 AND (4) 0.05-1% BY WEIGHT OF A HYDROPHILIC POLYETHYLENE GLYCOL DIESTER OF A C12-20 FATTY ACID, THE GLYCOL HAVING A MOLECULAR WEIGHT LESS THAN ABOUT
 500. 